Document: PHI-3-59-1

Changes in short- and long-term carbon storage following permafrost thaw in the boreal peatlands of Manitoba, Canada.

CAMILL, P.* ¹, J.A.LYNCH ², J.S.CLARK ² and J.B.ADAMS ²

Carleton College, Northfield, MN, 55057, USA ¹
Duke University, Durham, NC, 27708, USA ²

Abstract:
Permafrost thaw resulting from climate warming may dramatically change the succession and carbon dynamics of northern ecosystems. Several studies of tundra and upland boreal forests suggest that boreal and tundra biomes may become stronger sources of carbon as permafrost thaw improves soil drainage and hastens decomposition. Boreal peatlands may show a different response because permafrost thaw leads to wetter conditions and large changes in species, both of which impact peat accumulation. To examine the joint effects of regional temperature and local species changes on peat accumulation following thaw, we studied peat accumulation across a regional gradient of mean annual temperature (MAT). We measured short-term net annual above ground peat accumulation by estimating NPP, litterfall, and decomposition over two years for major functional groups. In addition, we collected six cores each from frozen and thawed bog communities to document long-term peat accumulation changes following thaw. Both short- and long-term analyses suggested that thawed bogs will probably remain a sink of carbon, although the direction of change in peat accumulation depends on regional climate. Short-term peat accumulation was significantly influenced by both local changes in functional groups and regional MAT. A few species, such as Picea mariana trees on frozen bogs and Sphagnum mosses in thawed bogs, sequestered a disproportionate amount of peat, and changes in their abundance following thaw changed carbon accumulation. Our results also suggested that short-term, above ground studies may underestimate the actual peat accumulation in cores. This discrepancy is partly explained by historical changes in functional groups that differ from modern communities.

Keywords: carbon, boreal, peatland, permafrost, climate warming

This abstract is being presented at: 10:30 AM in session:
CARBON STORAGE